Notes:

These dates and times are based on the Vernal Equinox figures printed in
Astronomical Tables of the Sun, Moon, and Planets, by Jean Meeus, 1983
published by Willmann-Bell, Inc., Richmond, Virginia 23235, U.S.A.
Mr. Meeus based his calculations on Simon Newcomb's theory as
given in Astronomical Papers American Ephemeris, volume VI part 1
published in Washington, 1895.

Responsibility for any errors is entirely mine.

The Gregorian Calendar did not exist before October 1582.
The equinox dates prior to October 1582, given above, are
expressed in the proleptic Gregorian Calendar. Likewise,
the modern arrangement, of dividing the surface of the Earth
into 24 time zones, did not exist before the 1880s. The equinox
times given above, for years before the existence of time zones,
are stated as if the modern system had been in existence earlier.